1. Field of the Invention
This invention relates to a roller mechanism for raising and lowering the screen of a roller blind.
2. Description of the Related Art
One conventional winding apparatus for roller blinds is shown in FIG. 5. In this type of apparatus, a winding roller 52 is rotatably supported at both ends by a support bracket 51. A blind screen 55 is fixed to the winding roller 52. A pulley 53 is provided at one end of the winding roller 52, and is rotatably driven integrally with the winding roller 52 by an endless cord to lift and lower the screen 55. When the cord 54 is not operated, the screen 55 is held at a predetermined position by a device (not shown) for preventing the lowering of the screen 55 due to the dead weight thereof. Japanese Unexamined Published Utility Model No. 63-106894 discloses a screen winding apparatus substantially similar to the apparatus described above.
Conventional winding apparatuses such as the one described above require a continuous pulling action on the cord 54 in order to rotate the winding roller to lift or lower the screen. This requirement makes the lifting and lowering operations relatively completed.